Sailboat of the catamaran type



Feb. 19, 1963 w. c. BEUBY 3,077,850

SAILBOAT OF THE CATAMARAN TYPE Filed June 19, 1961 4 Sheets-Sheet 2 t vo o "A INVENTOR William Charles Beuby ATTORNEY Feb. 19, 1963 w. c. BEUBY3,077,850

SAILBOAT OF THE CATAMARAN TYPE Filed June 19, 1961 4 Sheets-Sheet 5INVENTOR Feb. 19, 1963 w. c. BEUBY 3,077,850

SAILBOAT OF THE CATAMARAN TYPE Filed June 19, 1961 4 Shets-Sheet 4FIG.I5.

INVENTOR William Charles Beuby ATTORNEY FIG.I4.

3,077,856 SAILBOAT OF THE CATAMARAN TYPE William C. Benby, 2411 E. 25thPlace, Tulsa, Okla. Filed dune 19, 1961, Ser. No. 117,914 14- Claims.(Cl. 11 l39) This invention relates to a sailboat of the catamaran typewherein a pair of pontoons or hulls which resemble, more or less, thehull of an airplane are secured fore and aft to the lateral edges of adeck and are supported in flight by a longitudinal arrangement ofsurface-piercing hydrofoils. These hydrofoils are positioned slightlyaft of the center of gravity, on or slightly ahead of the aerodynamiccenter of pressure of the sail system and the boat is directed, trimmedand stabilized longitudinally by means of a pair of guidance andstabilizing hydrofoils located at the bow of the hulls. This sailboatcan be operated either as a conventional sailboat or as a hydroplane inthe event that ample wind velocity is available.

As will appear from the detailed description which follows, the moreimportant objects of the invention are comprised as follows:

Firstto provide a sailboat that is capable of attaining exceptionallyhigh speeds yet being useful and enjoyable in light weather.

Second-to provide a sailboat that can maintain its own trim withoutcomplicated mechanism or adjustment by the pilot or crew.

Thirdto provide a sailboat that has superior pointing capability and iseasily controlled as to direction.

Fourthto provide a sailboat that can be easily docked, safely flown athigh speeds, handled and transported more easily and which is low incost.

With these and other objects in view, my invention consists in the novelfeatures and advantages of construction and arrangement of parts whichwill be more fully understood from the following specifications,reference being had to the accompanying drawings wherein:

FIG. 1 is a conventional view, in side elevation, showing the relativepositions of the various hydrofoil and other elements; l l

FIG. 2 is a view, in side elevation, of the sailboat shown in FIG. 1;

FIG. 3 is a top plan view looking downwardly on line 3-3 of FIG. 1;

FIG. 4 is a view in perspective showing, conventionally, the relativepositions of the hull and deck centerboards or keels, the spacedfuselage shaped pontoons or hulls, the guidance and stabilizinghydrofoils, control means therefore, main lifting hydrofoils and otherdetails;

FIG. 5 is a sectional end view showing, in detail, a main liftinghydrofoil and a detachable band adapted to secure it to a respectivehull;

FIG. 6 is a detailed view showing a quick release for the band;

FIG. 7 is a detailed view showing means to attach a lifting hydrofoil toa respective band by inserting therebetween a frangible fail safeelement;

FIG. 8 is a broken away view of a mainsail showing means to attach it toa mast and associated streamlined shell or fairing;

FIG. 9 is an enlarged view, in detail, of a sail track formed in themast and an associated sail and mast fairing.

FIG. 10 is an enlarged view, partly in section, showing a quickdetachable rotary support for a stabilizing hydrofoil;

FIG. 11 is a front elevational view of the deck mounted centerboard;

FIG. 12 shows, in detail, a hull mounted centerboard or keel which isretractible and shockproof;

ice

FIG. 13 is a sectional view on line 13-13 of FIG. 12;

FIG. 14 is a detailed side view, partly in section, of the centerboardmountd on the rear deck in a manner to be either retracted or adjustedabout its vertical axis, and

FIG. 15 is a top plan view, in detail, showing a triangular shaped plateor deck section hingedly mounted adjacent to the forward edge of therear deck and which supports a vertical bearing for the centerboardshaft.

Referring to the drawings in detail, the hydrofoil sailboard accordingto the present invention and with particular reference to FIGS. 1 to 3,comprises, as the main elements thereof, similar fuselage shapedpontoons or hulls 1 and 2, a rear deck 3, a forward deck 4, a pair ofsimilar guidance and stabilizing hydrofoils 5 and 6, a pair of mainsimilar lifting hydrofoil units 7 and 8, a deck mounted centerboard 9and hull mounted centerboards 10 and 10.

A mast 11 and a boom 12 serve to support a mainsail 13. A common form ofrigging 14 is operatively connected to the mainsail while the boom iscontrolled by a sheetline 15 the free end of which is releasably securedto a head 16 shown in FIG. 4. A hollow strut 17 of streamlinecross-section is connected to and between the forward ends of the hulls.Each hull is provided with a plurality of openings 18 forming cockpitsto afford access to seats 19 and a canopy 20 covers, preferably, theforward pairs of cockpits.

Deck Mounted Centerboard The deck mounted centerboard 9, shown in FIG.14, is afiixed to a rotatable shaft 21 mounted in a suitable bearing 22and this centerboard, preferably, is streamlined in cross-section. Thiscenterboard and shaft unit is adjustable to various positions by meansof a control lever 23 and this lever can be locked in various positionsof adjustment thereof by means of a detent 24 mounted on the lever in amanner to engage a series of detents 25, deck mounted. The centerboard,as shown in FIG. 14, may be swung to assume a retracted positionparallel to the deck. A triangular shaped plate 26 serving as a bearingsupport is pivoted at 27 to the deck and the bearing 22 is held rigidlyby said plate. The plate 26 is positioned within an opening 28 formed inthe rear deck. When the lever 23 is raised, and swung forwardly, theplate 26 will swing clockwise on the pivots 27 to permit the centerboardto be elevated to a position parallel to the deck. A suitable detent 27'is pivoted at 28' and on a lock pin P. Before raising lever 23, pin P isremoved to permit 27' to swing a little counterclockwise. When lever 23is vertical, the detent 27' is returned to its locking position and itwill hold the lever 23 locked up. A pair of brace members 29 is securedas by welding to pivot lugs 30 and to the lower end of the bearing 22.The lever 23 may ride over the upper end of the bearing 22 or a collar22 on this lever may rest on this hearing.

The centerboard hydrofoil, which is to be used when the boat is sailedin light Weather as a conventional boat, extends some four feet into thewater vertically and has the unique feature of directional control. Itcan be directionally set in such a manner as to provide driftstabilization without the necessity of pointing the boat as in the casein conventional sailboats and is to be retracted when the boat is to beflown on the hydrofoil system. The hydrofoil centerboard rotates withthe shaft 21 which is located in the hydro-dynamic center of thevertical hydrofoil system so that the various positions may be selectedwith minimum eifort on the part of the crew operator.

Hull Mounted Centerboard In order to assure a proper drift stabilizationfor the type of hulls used on the sailboat disclosed when sailed as aconventional boat, an additional centerboard hydrofoiil of specialdesign is mounted in each hull at substantially the same location foreand aft as for the deck mounted centerboard hydrofoil 9. These hullmounted cemerooa as is; and w are adapted to be retracted into housingsor boxes 31 and the left hand centerboard is shown in detail in FIGS. 12and 13. Each box 31 is open at its upper end. The upper portion or endplate 32 of each centerboard normally remains completely housed withinin its respective box 31 and is formed to taper to provide a relativelywide upper edge. This end plate, if desired, may be thick enough to fita little loosely within its respective box. A stud 33 projects from eachside of the plate 32 at a point shown close to the hull bottom and eachstud is arranged to slide upwardly within a slot or groove 34 formed ineach side of the box 31. An elastic shock cord 35 connects the upper aftcorner of the plate at 35 to a point 36 on the box. In order to retractthe centerboard It shown, a cable 37 is connected at point 35' on theplate end 32 and is passed over pulleys 33 and 39 as shown. The lowerand slightly tapered end 40 of each hull centerboard is formed as shownin FIG. 13 more or less aeroform in cross-section from its lower end upto the bottom of the hull.

The left hand hull centerboard is shown in FIG. 13 as set at about adegree angle of attack or angle of incidence with respect to a lineparallel to the centerline of the boat or respective hull. The righthand centerboard is set, as to its 5 degree angle of attack, opposite tothat of the left hand centerboard. The use of these hull centerboardswill provide proper drift stabilization on the boat disclosed. Bysetting these two centerboards at the angle of attack described,additional effectiveness is obtained without significantly increasingthe drag so that one centerboard will perform the work of two with noangle of attack. The boat is sailed with only the leeward hullcenterboard foil extended in addition to the deck mounted centerboard 9.The centerboard box is designed to just accept the centerboard plate 32and loose enough to maintain it steady and is built strong enough towithstand the required side loads. After the centerboard is sliddownwardly through the upper open box top with the studs 33 within theslots 34, the shock cord and the retracting cable are fastened in place.By merely pulling this retracting cable, the centerboard will pivotaround the studs 33 clockwise to its horizontal position. Reversely, bymerely paying out this cable the centerboard will be rotated in acounter clockwise direction by the elastic shock cord 35 and the weightof the lower centerboard end.

This unique feature of yieldably mounting a hull centerboard is animportant part of my invention. If the centerboard strikes an objectwhile in forward motion, it will be deflected aft and up out of the wayor, if struck an upward blow or is forced upwardly, it will be displacedupwardly since it is not restrained as to position. A combination ofthese undesired forces acting on the centerboard might very well occurand the easiest and simplest deflection possible will be had.

Lifting Hydrofoils The main lifting hydrofoils 7 and 8 are locatedslightly aft of the center of gravity and on or slightly ahead of theaerodynamic center of pressure of the sail system. This hydrofoil systemprovides the main lifting force, supporting the boat in such a manner asto provide optimum maneuverability. Each lifting hydrofoil is removablymounted upon its respective pontoon by means of a band 41. To permitquick detachment, the free ends of the band are secured in a tightmanner by means of an old form of lever clasp or loop 42 pivotallymounted on one band end in a manner to engage a detent 43 affixed to theother cooperating band end. Each hydrofoil is secured to a respectiveband by means of two angular members 44 and 45 by means of bolts 46. Inorder to provide a fail safe feature, each member 44 and 45 is formedfrom Bakelite or similar frangible material. In the event that ahydrofoil unit engages an obstruction, the frangible supporting memberswill fracture in a manner to drop the unit to prevent damage thereto. Arestraining cable 47 is used to prevent loss of the released hydrofoilunit. The hydrofoil is adjustably held on its respective hull by meansof a spur gear 48 the teeth of which pass through an opening in the hulland engage holes 43 formed in the cooperating band. The shaft of thegear can be rotated by an electric motor or by a hand crank placedwithin the hull.

This novel form of band support permits the desired retraction of eachhydrofoil while docking by merely releasing a clasp 42 to permit theunit to drop by its own weight. A main feature of the lifting hydrofoilis that it can be quickly detached and stowed away on the forward deck.When it is desired to sail as a conventional sailboat, these hydrofoilswill be removed and all three centerboards will be used. However, whenthese hydrofoils are in use, the hull centerboards will remain retractedand need not be used.

Guidance and Stabilization System The guidance and stabilization systemcomprises a similar pair of hydrofoil units 5 and 6 supported rotatablyone unit at each forward end of a respective pontoon. Referring to FIG.10, a tubular shaft 49 is supported in a manner to be rotated within apair of upper and lower fittings or bearings 50 and 51. A cable drum 52is shown as affixed to said shaft to be rotated therewith and in amanner to be described. A second tubular shaft 53 is arranged within theshaft 49. In order to provide a means to cause the shafts to rotate inunison or to permit the inner shaft 53 to be readily detached from theouter shaft 49, a cap 57 is mounted on the upper shaft ends with thecircular cap flange 55 arranged to contact" and rotate on the fitting50. A bolt 56 is adapted to be passed through registering openings inboth shafts and this cap. A metallic plate 57 is afiixed to the lowerend of the shaft 53.

To provide for a fail safe feature for each guidance hydrofoil unit, theupper end of each unit comprises a plate member 58 formed from Bakeliteor similar frangible material which is secured as by bolts 59 to a platemember 57. Each unit comprises side members 60 forming a V-shaped and aplurality of dihedral shaped vanes 61. In the event that eitherhydrofoil unit might meet with an obstruction, the respective frangiblemember will become shattered at some point close to a corresponding endof a plate member 57. A restraining cable 52 is provided to prevent lossof the detached hydrofoil.

An important feature of the invention is the provision of a guidancecontrol whereby both guidance hydrofoils 5 and 6 can be rotated inunison from any one of the series of cockpits or by a crew memberstationed on the deck. As shown in FIG. 4, an endless cable 63 is passedthrough the strut 17 and is engaged around both drums 52 in the fronthull ends that serve to rotate the shafts 49 and 53. A second cable 64also engages, in the bight thereof, around a respective drum and the twocable ends are extended rearwardly to pass each cockpit in one hullthence around pulleys 65 and 65' to permit each cable to be accessibleat a deck crewman position 66. At each cockpit, a foot operated lever 67functions to control the cable 64. A third and similar cable 68 isprovided to cooperate with each cockpit in the other hull and the freecable ends extend, also, to said crewman position 66.

Mast Track and Streamlined Casing The mast is formed with a track orchannel69 which is substantially closed except for a narrow opening 70'5 through which the leading edge of the sail projects. A bead 71 isformed on said leading edge by sewing or otherwise securing a rope 72into this edge. This rope is solid enough to retain its shape as it isintroduced into the track and slid upwardly into position along the fulllength of the mast.

As a means to reduce head resistance to the mast as well as to reducethe formation of eddy currents around the mast which might impair theefliciency of the sail and affect air currents on the leading face ofthe mast, I provide a fairing or casing 73 stream-lined in cross-sectionin position to surround the mast. The trailing edge of this casing isprovided with a narrow opening 74 that receives the sail. If desired,the sail may be reinforced along the zone thereof that engages thecasing ends that contact the sail. The casing is arranged to rotatefreely around the mast so as to follow all lateral movements of the sailthereby to reduce the efiects of the objectionable eddy currents uponthe sail. This mast casing will form a continuation of the sail up toand somewhat in advance of the mast.

In view of the foregoing detailed description, it should be obviousthat, in the boat disclosed, a reduction of wind resistance andconsequent increase in efliciency is obtained due to such factors ashousing the crew within canopy covered cockpits, use of streamlined mastshell and hulls as well as the use of a deck section and forward cablehousing strut that are of airfoil shape.

Longitudinal stability is obtained by locating the stabilizationhydrofoil system at the bow of catamaran hulls. Each hydrofoil assemblyis made up of foil elements of a well known hydrofoil cross section, andof small cord for efficient high speed operation. These elements shapedwith a decided dihedral are spaced vertically. Each whole assembly thusforms a V shape and is mounted on an axis tilted about to keep theresultant hydrodynamic forces on the foil system within the plane of theaxis while the boat is foil borne.

Each foil element, having the proper angle of incidence, exerts aseparate lifting force. The total lifting force exerted at any timeincreases very rapidly with the degree of submergence of the hydrofoilassembly. An increase in the wind velocity momentarily increases thesail thrust forward which tends to depress the bow of the boat. Thestabilization hydrofoil assemblies being submerged to a greater depthwill instantly exert a greater lift, immediately counteracting thisincreased sail thrust and thus re-establish the trim of the boatautomatically. Since the boat is supported primarily by the main liftinghydrofoil system just aft of the center of gravity, the trim changesrequired by movement of the crew and variation in wind velocity willrequire little force to correct. With this arrangement of thesehydrofoil systems, especially effective trim control is realized.

Lateral trim or stability is attained, first by reason of the wide treador distance between the main lifting hydrofoils made possible by the useof the catamaran type boat and, second, because of the design of themain hydrofoil system.

This system is made up of two assemblies, one for each hull, which haveelements of a well known hydrofoil section of small cord for efiiciencyat high speeds. These lifting elements, or foils, are spaced verticallyto eliminate hydrodynamic interference between lifting surfaces, andextend from the inner in the outer struts to which they are welded. Theelements are perpendicular to the outer strut and therefore exert atotal lifting force parallel to the outer strut which increases with thedegree of submergence of the assembly as a whole.

As the boat is subjected to a side load due to an increase in windvelocity or a change in wind direction, the leeward hydro-foil assemblywill be depressed or submerged to a greater depth. This increase insubmergence immediately increases the lifting force exerted by this foilassembly which tends to right the boat. The sail force is thusinstantaneously counteracted with the result that the boat isimmediately stabilized in a natural manner without any action on thepart of the pilot or screw.

Variations in the direction of the sustaining force can be attained byrotating the hydrofoil assembly about the hull to different settings.This makes it possible, for instance, to increase the efficiency of thesystem while going before the wind, which requires no driftstabilization, by rotating both the right and left hand assemblies sothat the lifting force is vertical to the surface of the water. Eachsubmerged element would be thus lifting to its maximum efiiciency. 1

When the boat is foil borne, drift stabilization is attained by settingthe windward main foil assembly so that the lifting force is verticalwhile the leeward main foil assembly is still working to oppose the sailforce. With this arrangement, the boat would actually crab to thewindward momentarily as the wind velocity would intermittently diminishin intensity. This would also achieve the most desirable objective ofmaintaining the apparent wind direction constant without loss of headmg.

This same result is achieved when the boat is sailed as a conventionalcatamaran by reason of the unique hydrofoil centerboard arrangement onthis boat. The leeward hull centerboard foil is lowered and the deckcenterboard foil is set at a 5 heading in the same direction as that ofthe lee hull centerboard foil. With both of these exerting a forcecounteracting the effect of the wind against this sail, when this windmomentarily diminishes this side force is correspondingly reduced andthe boat thus unopposed would crab to the windward, thus gaining inposition closer to the wind. Again the secondary effect of this actionwould make it possible to maintain a constant apparent wind directionand continue to realize the advantages of this eflicient attitude ofsail with respect to wind direction.

The boat is supported substantially at its center of gravity andtherefore can be directionally controlledwith great efficiency. Sincethe guidance system is at the bow of the boat, its turning moment isgreat and directional changes are easily made. In addition, the factthat the guidance system is hydrodynamically balanced further reducesthe pilot effort required to turn the boat, it responds instantaneouslyto the touch of the rudder pedals.

- Docking is made easy by means of the adjustable feature of the mainlifting hydrofoil assembly attaching band. This band, which normallyholds the hydrofoil assembly securely in position, can be easilyloosened and the assembly can be repositioned vertically below the hullto clear the side of the catamaran to come along side the dock. Thisadjustment can be made quickly by simply bringing the boat into thewind, permitting the boat to placed in the desired position.

The breakaway or fail-safe feature is important because it is necessaryto entirely remove the hydrofoil assembly from the boat rather thanpermit it to be distorted or displaced which might result in someadverse loads of considerable magnitude. There is also a secondaryadvantage gained by this breakaway feature which concerns the reductionof the probable damage to the basic hull structure when encounteringobstructions As a result, the boat can be more safely flown at highspeeds.

This boat is constructed of lightweight low cost material as fiber glasswhich assures an economy which is reflected in low production costs andtherefore a reasonable purchase price. Also, the boat is simple indesign and has no complicated mechanism. A preferred width of eight feetwill permit safe road trailering.

While a preferred form of the invention is disclosed and various detailsthereof, it is to be understood that various modifications arecontemplated such as would be included within the scope of the appendedclaims as follows:

I claim:

1. A sailboat of the catamaran type comprising a pair of spaced fuselageshaped hulls, a deck secured rigidly to and between said hulls, eachhull being provided with a main lifting hydrofoil unit positionedslightly aft of the center of gravity of the respective hull, a quicklydetachable means for supporting each of said units, said meanscomprising a band encircling each of said hulls, each band including aquick release device for opening either hand to permit removel of therespective unit.

2. In a sailboat as set forth in claim 1 wherein the deck is providedwith openings through which the bands are adapted to pass freelywhereby, during docking of the boat, the units are permitted to drop bygravity upon operation of the quick release devices and extendvertically.

3. In a sailboat as set forth in claim 1 wherein each hydrofoil unit issupported by a respective band by means of an interposed frangibleelement whereby, if the unit meets with an obstruction, said unit willbe released quickly from the band.

4. In a sailboat as set forth in claim 1 wherein a forward portion ofthe deck is formed aerofoil in shape in fore and aft section.

5. In a sailboat as set forth in claim 1 wherein the forward ends of thehulls are rigidly interconnected by a transverse strut, said strut beingof aerofoil shape in a manner to provide lift during forward motion.

6. A sailboat of the catamaran type comprising a pair of spaced hullsinterconnected by a deck, a guidance and stabilizing unit rotatablymounted on and at the forward portion of each hull, each unit having acylindrical hearing member extending upwardly and rearwardly througharespective hull and terminating above the hull, a control sleevesupport surrounding said bearing member, means to detachably interlockthe bearing member to the control, sleeve, a control element afiixed toeach sleeve and a cable engaged with both elements whereby rotation ofeither element will cause rotation of the other element.

7. In a combination as set forth in claim 6 wherein the upper ends ofthe bearing member and the control sleeve are provided with means forreleasably locking the memher and sleeve whereby removal of the lockingmember will permit quick detachment of a respective unit.

8. In a combination as set forth in claim 6 wherein each hull isprovided with cockpits, a foot operable lever positioned at eachcockpit, main control cables in engagement with each control element, anend of each control cable being connected to the foot levers in eachhull whereby the control cables may be operated by any member of thecrew.

9. In the combination set forth in claim 6, a streamlined strut rigidlyconnected to and between the forward ends of the bulls, the controlelements being positioned adjacent respective ends of the strut and saidcable being located within the strut.

10. In the'combination set forthin claim 6 wherein a frangible elementis positioned between the upper end of each unit and a respectivecylindrical bearing, said element being adapted to breakin a manner torelease the unit in the event that a respective unit encounters anobstruction.

11. A sailboat of the catamaran type comprising a pair of spaced hullsinterconnected by a deck, said deck being provided with an opening, adeck section pivotally mounted in said opening in a manner to swingdownwardly and rearwardly, a centerboard having a vertically extendingshaft, a bearing mounted on said section, said shaft being rotatablysupported within the bearing, a rearwardly extending handle on saidshaft for swinging the centerboard laterally, said handle beingoperative, when moved up wardly and forwardly, to swing the centerboardrearwardly to a retracted position close to the lower side of the deck.

12. A sailboat of the catamaran type comprising a pair of spacedfuselage shaped hulls, a deck secured rigidly to and between said hulls,each hull being provided with a main lifting hydrofoil unit positionedsubstantially intermediate of the ends of the hull and on or slightlyahead of the aerodynamic center of pressure of the sail system butslightly aft of the center of gravity of the boat, each main hydrofoilhaving a pair of lateral supports connected to opposite sides of arespective hull and converging downwardly, a guidance and stabilizingunit of the hydrofoil type positioned on and below the forward endportion of each hull each guidance unit comprising transverse vanesdecreasing in area downwardly whereby depression of the bow due to anincrease in windvelocity and sail thrust will be counteracted by anincreased lift on the bow and due to increased submersion of saidstabilizing units, each last named unit being rotatably mounted on arespective hull and control means for rotating said last named units inunison.

13. A sailboat of the catamaran type as set forth in claim 12 wherein ashaft is rotatably mounted on each of the forward hull ends and beingextended downwardly to a point below the respective hull end, eachstabilizing unit being supported on the lower end of a respective shaft,the control means being associated with said shafts and including anoperating element therefor which is extended to an operating position onthe boat. p

r 14. A sailboat as set forth in claim 12, a band encircling each hulland being adjustably mounted thereon, the main lifting hydrofoil unitsbeing supported on said bands and means for adjusting the position ofeach band and the hydrofoil supported thereon while the sailboat is inflight.

References Cited in the file of this patent UNITED STATES PATENTS1,410,875 Baldwin Mar. 28, 1922 2,561,253 Wells-Coates July 17, 19512,703,063 Gilruth Mar. 1, 1955 2,856,878 Baker Oct. 21, 1958 2,991,749Patterson July 11, 1961 OTHER REFERENCES Catamarans 1958, A. Y. R. S.publication No. 22, pages 20 and 34, published by John Morwood.

1. A SAILBOAT OF THE CATAMARAN TYPE COMPRISING A PAIR OF SPACED FUSELAGESHAPED HULLS, A DECK SECURED RIGIDLY TO AND BETWEEN SAID HULLS, EACHHULL BEING PROVIDED WITH A MAIN LIFTING HYDROFOIL UNIT POSITIONEDSLIGHTLY AFT OF THE CENTER OF GRAVITY OF THE RESPECTIVE HULL, A QUICKLYDETACHABLE MEANS FOR SUPPORTING EACH OF SAID UNITS, SAID MEANSCOMPRISING A BAND ENCIRCLING EACH OF SAID HULLS, EACH BAND INCLUDING AQUICK RELEASE DEVICE FOR OPENING EITHER BAND TO PERMIT REMOVEL OF THERESPECTIVE UNIT.